Stereophonic loud speaker or instrument



Feb. 23, 1965 P. M. SULLIVAN ETAL 3,170,537

STEREOPHONIC LOUD SPEAKER 0R INSTRUMENT Filed Jan. 21, 1963 my 5 my 6' Pafflc-A M Ju/// van Gare/d fl. Jear:

INVENTORS way/$04 A fro/w: m

3,170,537 STEREOPHONIC LOUD SPEAKER OR INSTRUMENT 7 Patrick M. Sullivan, 3755 Grammercy, Houston 25, Tex

and Garold D. Sears, 5634 Eskridge, Houston 23, Tex. Filed Jan. 21, 1963, Ser. No. 252,988 7 Claims. (Cl. 181-31) Thepresent invent-ion relates to a speaker or instrument that receives a single signal voltage representing the frequency range from the lower frequency limits through the upper frequency limits of human hearing and which reproduces stereophonic sound having the frequency range represented by the single signal voltage.

Stereophonic sound equipment in use at the present time requires the use of dual channel recording or transmitting techniques, and the sound is then reproduced through dual channel receiving equipment. Each channel of the receiving equipment includes two or more I speakers, and a portion or segment ofthe audio frequency; range is conducted through a particular speaker that has characteristics which match the frequency rangetransmitted thereto.

listener is then positioned in proper relation to the speakers,. a stereophonic sound effect is produced.

When the speakers are physically positioned in proper relation to each other and when the United States Patent 3,170,537- Patented Feb. 23, 1965 as well as the distance relationship of the listener to-tlie' speakers.

Accordingly, it is an object of the present invention to provide a stereophonic loud speaker or instrument which is responsive to a single signal voltage that represents the total frequency range from the lower frequency limits through the upper frequency limits of human hearing and which reproduces stereophonic sound having the. frequency range represented by the signal voltage with great fidelity. 1

Yet another object of the present invention is to pro- 7 plurality of parallel spaced'panel members, one of which V is connected to said converting means whereby the vibrations from saidconverting means are imparted thereto,

' said panel members being constructed and arranged It can be appreciated that the foregoing general del I scription of present devices for producing stereophonic sound has many limitations and disadvantages. The recording or transmitting techniques and the receiving and reproducing instruments and equipment greatly increase the original cost of the equipment and the cost of the production andreproducing equipment. Furthermore,

theelectronic circuitry involved in the system causes,

some unwanted noise and interference and tends to whereby a frequency range of vibrations may be selectively concentrated in predeterminedareas of saidpanel i means whereby the device functions to reproduce stereophonic sound havingthe total frequency range repre a sented by the signal voltage.

Yet a further object of the present invention is to pro- 7 videa sound reproducing instrumentincludinga plurality reduce the fidelity of sound as compared with its original production in a live state. employed in the system cannot reproduce with any greater fidelity than the signal voltage transrnitted to them through the electronic circuitry, nor can they reproduce any frequency range other'than that which is conveyed to them. Therefore, present speakers, as single .loud speaker devices, are restricted intheir frequency range reproducing capabilities, and they do not reproduce complex sound compositesv of wide frequency range in high fidelity to the live state.

Furthermore, the speakers In an attempt to overcome this deficiency, various prior 7 art devices have employed the use of multiple speakers, as previously noted, each having more proficiency in one frequency area than theother. Also, various adaptations of speaker mountings, have been attempted in cabinets or enclosures, but such enclosure mountings do not form molecular structure of the panelswhich in turn imparts 1 an integral part of the speakers and merely improve the acoustics to the listener. It can be appreciatedthat this arrangement also requires electrical transmissions to the various speakers by selective frequency area corresponding to the proficiency of the speaker as previously noted,

and this, in turn, requires filtering systems, cross-over net- Works, or compensating electrical signal transmissions to maintain balancebetween the various speakers'as a combined unit output.

Accordingly, since all loudspeakers, whether used in 1 multiple relationship'or individually, do not in themselves have stereophonic capabilities; with respect to reproducing sound and since they may only reproduce ,in

to them, any resulting stereophonic effect from the presof spacetd panels providingan air volume therebetween, there being means to impart-vibrations in the panels representing thefrequency range from a single signal voltage.

from the lower frequency limits. through the upper frequency limits of human hearing, which vibrationsare imparted from the molecular structure of the panel to the air volume therebetween, said panel ineansbeing con structed and arranged to selectively-concentrate in predetermined portions or areas thereofi a frequency range of vibrations predominant relative tolthe total frequency range; represented by the signal voltage to thereby reproduce stereophonically the total sound represented by the single signal voltage.

Still a further object of the present invention is to provide a sound reproducing instrument including a plurality of parallel panels connected by bridgingposts and providing an air' volume, means to impart vibrations to the sound vibrations upon the molecularv structure of the air inthe air volume, said vibrating meansbeing responsive ,to a single signal voltage representing the frequency range from the lower frequency limits through the upper frequency limits of human hearing, said panels being constructed and arranged so that they may be tuned to repro duce stereophonic sound having the frequency limits represented by-the single signal voltage.

Still a further .object of the present invention is to providea stereophonic loud speaker which receives a single signal voltage representing the frequency range from the lower frequency limits through the upper frequency limits of human hearing and which stereophonic speaker is c'on'stiuicted and arranged so as to reproduce a r stereophonic sound havin the fre uen form and character the electncal signal values imparted g q range repre sented by the single signal voltage, and each frequency range of the stereophonic sound having a position from left to right in'the speaker as heard by the listener and having basethrough treble frequencies.

Still a further object of the present inventionis to and multiple provide a high fidelity sound reproducing instrument which receives a single signal voltage representing the frequency range from the lower frequency limits through the upper frequency limits of human hearing and which stereophonically separates and reproduces the sound represented by the single signal voltage, all of which is accomplished Without the employment of multiple loud speaker units separated by distance and which is accomplished without the use of dual channel recording or amplification techniques.

A further object of the present invention is to provide a sound reproducing device which may eifect stereophonic reproduction of orchestral renditions in which the reproduction has a continuity between the instruin both a sense of expanse with a sense of depth without loss, of continuity of the musical score during the 'stereophonic separation.

Yet a further object of the present invention is to providea sound reproducing instrument which may effect 7 stereophonic reproduction in'which the listener may experience the stereophonic effect in any position on a perimeter up to at least 140 in front of the invention.

Yet a further object of the present invention is to provide a sound reproducing instrument which includes a plurality of parallel panel means to thereby provide a plurality of surface areas in contact with an air volume between the panels, there being means to secure the panels together and there being means to impart a vibration to said panel means representing the frequency range from the lower frequency limits through the upper frequency limits of human hearing, said vibration imparting' means imparting vibrations to the molecular structure of the panel means which in turn induces a sympathetic vibration in the air molecules and said panel means being constructed and arranged so that a predetermined frequency range of'vibrations may be concentrated or predominated in a predetermined area of the panel means to thereby reproduce stereophonically the frequency range represented by the single signal voltage.

Still a further object of the present invention is to provide a sound reproducing device including a plurality of'parallel panel means spaced to provide an air volume in the device, which device and air volume define an arrangement having height, width, and depth which yields a dimensional cubic capacity and means for imparting audio vibrations in the molecular structures of said panel means from a singlesignal voltage, which in turn, induces the vibrations into the air volume in the device, said vibration imparting means being responsive to the single signal voltage representing the frequency range from the lower frequency limits through the upper frequency limits of human hearing, and'said panel means being constructed and arranged so that the vibrations imparted thereto may beselectively concentrated and predominated in certain areas of the panel means in relation to a predetermined or desired frequency range. to thereby reproduce stereophonic sound having the frequency range represented by the single signal voltage. 1 i

Another object of the present invention is to provide a sound reproducing instrument which is a high fidelity stereophonic loud speaker in its entirety without the requirement ofselective signal transmission to its electromechanical parts or without the employment of filtering systems or crossover networks and which does not require special enclosure mounting for improved effect by acoustic means.

Other objects and advantages of the present invention will become more readily apparent from a consideraor a preferred form of the present invention;

FIG. 2 is a top plan view showing the form of the invention of FIG. 1 in assembled relationship;

FIG. 3 represents alternate embodiments of one of the panel means employed with the present invention;

FIG. 4 is an enlarged view illustrating in greater detail the manner of securing the vibration imparting means in relation to the panel means or members;

FIG. 5 illustrates an alternate form of vibration im parting means; and

FIG. 6 illustrates another embodiment or form of the vibration imparting means which may be employed with the present invention.

Attention is first directed to FIG. 2 of the drawings wherein a preferred embodiment of the speaker or instrument of the present invention is referred to generally by the numeral 16. It can be appreciated that this embodiment is illustrative of the concept of the invention, and many variations in form, size, and shape may be made without departing from the scope of the invention.

In FIG. 2, a plurality of panel means designated generally at 11 are provided, which panel means in the embodiment illustrated in FIG. 2 includes a front panel 12, an intermediate panel 13, and a rear panel 14, all

of which are spaced relative to each other to provide cavities 16 and 17 between the front and intermediate panel and the intermediate and rearpanel, respectively.

The cavities 16'and 17 provide air volumes correspond- 13, and 14 in a manner as will be described in greater detail hereinafter. Y

It'will be noted that the intermediate panel 13 as illustrated in FIG. 1 of the drawings is provided with openings 18 and 1? therein wherebyv the air volumes in the cavities 16 and 17 are communicated. Suitable means are provided for imparting vibrations to the panel means 11 and theair volumes in the cavities 16 and 17, such means being represented generally by the numeral 21. As illustrated in the drawings, a pair of such vibration imparting means is illustrated, and the vibration imparting means 21 includes the member 23 which is a standard voice coil to which a signal voltage may be applied in any manner well known in the art. The member 23 is constructed so that it is responsive to a signal voltage that represents the frequency range from the lower frequency limits through the upper frequency limits of human hearing and the signal voltage impressed' upon each of the members 23 of the vibration imparting means 21 is the same signal voltage. Also forming part of the vibration imparting means is the cone member 24. It will be noted that one cone member is provided for each of the members 23 as illustrated in FIG. 2 of the drawings. The members 23 and'24 function in awell known manner to impart vibrations to the cone member 24, and when a single signal voltage representing the audible frequency range from the lower frequency limits through the upper v frequency limits of human hearing is impressed upon the i by screws or any other suitable means that firmly fixes and secures the member 23 to the panel 13.

The cone member 24 is positioned relative to the member 23 in a manner well known in the art, and its outer annular lip 27 is secured to another of the panel members such as the front panel 12 by; any suitable means such as a ring 28 which abuts and rests on the annular lip 27 and throughwhichscrews 29 or the like may be secured so as to firmly position the cone 24 on the member 12 whereby vibrations from the cone 24 may be imparted to the molecular structure of thepanel 12.

The front panel 12' is secured to and spaced from the panel 13 by a plurality of bridgingpost means which are in the portion of panel 12 surrounding one of the V cones 24, audit will be noted in the form of the invention as illustrated in FIG. 2 four of such bridging post means are provided. The bridging post means 30 is in the form of a plurality of separate pegs which may be secured to the intermediate panel 13 by any suitable means such as by gluing or the like so that they become an integral part of the intermediate panel 13, and they are secured to the front panel 12 by gluing or the like in a manner so that the cone 24, front panel 12, and intermediate panel 7 13 are formed into a single unit.

Similarly, bridging post means 31 are provided which surround the second cone 24, and these bridging post means 31 integrally connect the portion of the front panel 12 with which they are connected to (the intermediate panel 13. Similarly, bridging post means 32 are provided for firmly securing therear panel 14 to the intermediate positioned in any relationship relative to the cone 24 which they surround so as to not interfere with'the imparting of the vibrations from the cone 24 to the portion of the front panel 12 therearound and thence through the bridging post means 30 to the intermediate panel 13 and through the bridging post means 32 to the rear panel 14. Similarly, thebridging post means 31 which secure the portion of the panel 12 to the cone 24 on the right-hand side of the device as viewed in FIG. 2 of the drawings are mounted so that the vibrations imparted to the panel portion 12 by the cone on the right side may in turn be imparted through the bridging post means 31 to the intermediate panel 13 and then rear panel 14.

An additional bridging post 40 is provided which extends from the portion of the front panel 12 associated with the cone 24 and through the opening 19 formed in the intermediate panel 13 andis integrally connected with the rear panel 14 as illustrated in the drawings for conducting lower frequency vibrations directly to the rear panel 12. In the embodiment of the invention illustrated in FIGS. 1 and 2 of the drawings, the front panel 12 is separated into two panel portions 12a and 12b, the portion 12a is secured by the bridging post means 30 to the intermediate panel 13'and by post 40-to panel 14, and the. front panel portion 12b is secured by bridging post means 31 .to the intermediatepanel 13. It will be further noted that the area of the panel portion 12a is greater than the area of the panel portion 12b, and whilethis area may be varied,

, it has been found that most effective results are obtained when the panel portion 12a represents approximately 60% to 75% of the total area of front panel 12 including mem- 'bers 12a and members 12b. Also, it will be noted in the form of the invention shown in FIGS. 1 and 2 of the drawings that the panel portion 12b is less in thickness than the panel portion 12a. It will be further noted that the intermediate panel 13 is of greater thickness than the front panel 12, and may, if desired, be of greater thickness than the rear panel 14.

wood. However, it can be appreciated that these thicl! nesses may be varied within certain limits, and it can be furtherappreciated that the total size and volume of air in cavities 16 and 17 formed in the device will effect the fidelity of reproduction.

In the use of the present invention, a single signal voltage is simultaneously impressed upon each of the voice coils 23, and this single signal voltage represents the frequency range from the lower frequency limits through the upper frequency limits of human hearing and represents the sound which is to be reproduced stereophonically by the invention 10. Vibrations are imparted to cone 24 on the left of the device by the member 23 in a manner well known in the art, and these vibrations are imparted to therpanel member 12a. By reason of its area relationship and thickness in relation to the panel member 12b, the lower frequency range repre-.

senting the bass is thereby concentrated in the panel 12a predominantly relative to the total frequency range of the vibrations imparted to the member 12a. Similarly,

-, the thinner panel ear of panel portion 12b concentrates predominantly the higher frequency range therein from the right cone 24 representing the treble in proportion to the total vibrations imparted thereto from the single voltage impressed upon the vibration imparting means 21. connected therewith. As previously noted, the bridging post means 30 connected in panel portion 12a and bridging post means 31 connected in panel portion 12b are arranged relative to cones 24 so as not to dampen the vibrations imparted to the respective panel portions.

Thus, the vibrations imparted to the molecular structure of panel portions 12a and 12b are in turn imparted to the panel member 13 and panel 14 and are thus sympathetically induced into the air molecules in the air volumes in the cavities 16 and 17. Since a predetermined range of frequencies is concentrated on the left side of the device as viewed in FIGS. 1 and 2 of the drawings in relation to the total frequency imparted thereto and since the higher frequencies are concentrated on the right side of the device as viewed in FIGS. 1 and Tim relation to the total frequency imparted thereto, the device functions as a single speaker or instrument to reproduce stereophonic sound from the single signal voltage impressed upon the vibration imparting means 21.

As previously noted, the bridging posts 30, 31, and 32 are arranged in the unitary structure so as to not interfere or impair the transmission of vibrations through the structure, and the relationship of structural areas and air volume in the structure yields a sound which is stereophonic in effect and which may be enjoyed by the listener on any perimeter of at least up to in front of the invention 10.

As a practical matter while thicknesses of the front plate 12 may vary, the thinnest front plate 12a and 12b which produces most satisfactory and desirable results is approximately one-quarter inch, while about three-eighths inch is the most desirable maximum thickness of .the front plate 12. The center plate 13 may vary from about onehalf inch to one inch, and its preferred thickness is about three-quarters inch. The rear panel 14 is preferably one-quarter inch to one inch in thickness. In some instances, it may be desirable to completely abandon the rear panel 14 so that the panels 12 and 13 may be mounted on a wall. As previously noted, the cubic capacity of the invention effects the acoustic output, and it can be appreciated that the panels 12, 13 and 14 may bemade of suitable dimension to attain the listening results desired.

Also, the plates 12, 13 and 14, are shown as being in parallel relationship which represents the preferred arrangement, but in some instances, it may be desirable to arrange them in other than parallel relationship.

, In FIG. 3, an alternate form of the panel 12 is illustrated, and it will be noted that the panel 12 is there shown as being integral as opposed to the separated portions 12a and 12b shown in FIGS. 1 and 2.

However, it will be noted that the cone 24 is mounted in a portion 12c which is divided off by the separation grooves 41 from the portionlzd and that the portion 12c is larger in area than the portion 12d. Similarly, an opening 42 provides an area separation means as shown in FIG. 3 for another form of plate 12 so that the areas 12c and 12d may be responsive, respectively, to the cones 24- secured thereto. The cones 24 act upon the areas 120 and 12d, respectively, in a manner as described with regard to the areas 12a and 121) so as to concentrate or predominate a certain frequency range of vibrations therein in relation to the total frequency range imparted to each front plate portion by the single signal voltage acting on vibration imparting means 21.

In FIG. 5, an alternate form of the cone is illustrated and is shown as being in the form of a tube 45, the tube 45 being mounted relative to a voice coil 23 that is similar to the voice coil 23 described with regard to FIG. 1 and also being secured to the panel 12 by suitable means such as a ring 28 engaging the annular lip 27 on the tube 25 and held thereagainst by screws 29 or the like.

In FIG. 6, still another form of the tube is illustrated at 46 wherein its outer annular lip 27 is again secured by a ring 28 with screws 29 therethrough whereby it is integrally connected to the plate 12. The form of cone 24 is not critical as noted above, and the form of cone shown in FIGS. and 6 may be employed so as to impart vibrations to the molecular structure of the panel means 11 in the manner as described with regard to FIGS. 1 and 2.

It will be noted that when the device of the present invention is assembled, an integral unit is formed which is a speaker or sound reproducing instrument adapted to receive a single signal voltage and concentrate or predominate selected frequencies in a selected area and volume of the device to thereby reproduce stereophonic sound.

It will be further noted that the sound which is stereophonically reproduced is received from a single signal voltage representing the entire frequency range from the lower frequency limits through the upper frequency limits of human hearing, and the stereophonic effect is produced without the use of dual channels or electronic circuitry or multiple speakers.

In listening to the device, the listener receives the effect of stereophonic sound as the lower frequencies are concentrated in the left side of the device, and the higher frequencies are concentrated in the right side of the device. Thus, the bass is reproduced from the listeners left, the middle range of frequencies from the central portion, and the highest frequencies are received progressively to the right. The device produces a sound from the lower frequency range through the higher frequency range of human hearing, and the sound is reproduced in relation to a position extending across the front of the device so that a stereophonic effect is conveyed to the listener.

The device may be formed of any suitable material the molecular structure of which will respond to the vibrations imparted thereto to produce the desired results.

What is claimed is:

1. A sound reproducing instrument for stereophonically reproducing audio frequencies from a signal voltage the frequency and amplitude of which represent the total sound to be reproduced comprising,

(a) means for receiving a signal voltage the frequency and amplitude of which represent the total sound to be reproduced,

(b) means for converting the received signal voltage into vibrations the frequency and amplitude of which represent the total sound to be reproduced,

(0) panel means secured to said converting means whereby the vibrations are imparted to said panel means,

(at) additional panel means secured to but spaced'from said first named panel means whereby the vibrations from said first named panel means are also imparted to said additional panel means and the space between said panel means and additional panel means providing an air volume in which the vibrations may be induced, and

(c) said panel means and said additional panel means having predetermined areas which selectively concentrate a frequency range of vibrations in said predetermined areas of said panel means and additional panel means to thereby stereophonically reproduce the total sound represented by the signal voltage.

2. A sound reproducing instrument for stereophonically reproducing audio frequencies from a signal voltage the frequency and amplitude of which represent the total sound to be reproduced comprising, i

(a) a pair of members for receiving a signal voltage the frequency and amplitude of which represents the total sound to be reproduced,

(b) means associated with each of said members for converting the received signal voltage into vibrations the frequency and amplitude of which represents the total sound to be reproduced,

(0) panel means secured to each of said converting means whereby the vibrations are also induced in said panel means,

(d) said panel means having a larger area of approximately 60% to of the total area of said panel primarily responsive to one of said converting means and the remaining smaller area of said panel primarily responsive to the other converting means to thereby selectively concentrate in said larger and smaller panel areas respectively a frequency range of vibrations from each of said converting means,

(e) additional panel means spaced from said first named panel means providing an air volume in the instrument in which the vibrations from said larger and sinaller areas may be induced,

(f) bridging post means connected with said first named panel means in its larger area and to said additional panel means,

(g) bridging post means connected with said first named panel means in its smaller area and to said additional panel means, and

(11) said bridging post means also conducting to said additional panel means the vibrations from said larger and smaller areas respectively of said first named panel whereby the instrument stereophonically reproduces the total sound received by said members from the signal voltage.

3. A sound reproducing instrument for stereophonically reproducing audio frequencies from a signal voltage the frequency and amplitude of which represent the total sound to be reproduced comprising,

(a) a pair of members for receiving a signal voltage the frequency and amplitude of which represents the total sound to be reproduced,

(b) means associated with each of said members for converting the received signal voltage into vibrations the frequency and amplitude of which represents the total sound to be reproduced,

(c) a panel approximately inch in thickness secured to one of said converting means whereby a selected range and frequency of vibrations from said converting means are predominately imparted to said panel,

(d) a panel approximately 4 inch in thickness secured to the other of said converting means whereby aselected range and frequency of vibrations from said other converting means are predominately imparted to said panel secured thereto,

(c) said inch panel having a surface area in the range of approximately one and one-third to three times as large as the surface area of said /4 inch panel,

(f) a panel of approximately inch in thickness spaced from said /3 inch and A inch panels providing an air volume responsive to the vibrations in said panels,

(g) bridging post means connecting said inch panel and said A inch panel to said inch thick panel whereby the vibrations in said inch and A inch panels are imparted to said inch panel,

(h) an additional panel spaced from said /4 inch panel to provide an additional air volume responsive to the vibrations in said panels,

(i) bridging post means connecting said inch panel and said last named panel there being opening means in said inch panel for communicating all of said air volumes,

(j) a bridging post connected to said inch panel and extending through the opening in said inch panel to be connected to said additional panel for transmitting the vibrations received by the bridging post to said additional panel, and

(k) all of said panels and air volumes cooperating to stereophonically reproduce the total sound represented by the signal voltage.

4. A sound reproducing instrument for stereophonically reproducing audio frequencies from a signal voltage the frequency and amplitude of which represent the total sound to be reproduced comprising,

(a) a pair of members for receiving a signal voltage the frequency and amplitude of which represent the total sound to be reproduced,

(b) means associated with each of said members for converting the received signal voltage into vibrations the frequency and amplitude of which represent the total sound to be reproduced,

(c) a front panel means including a portion with which one of said converting means is connected and a portion with which the other of said converting means is connected,

(d) said panel portion with which said one converting means is connected representing approximately 60% to 75% of the total area of said panel means and said panel portion with which said other converting means is connected representing the remaining area of said panel means whereby a selected range and frequency of vibrations from said members is predominated in said respective panel ortions,

(e) an intermediate panel spaced from and parallel to said front panel means to provide an air volume which is responsive to the vibrations imparted thereto,

(f) bridging post means connecting each of said panel portions with said intermediate panel to impart their respective vibrations thereto,

(g) a rear panel spaced from and parallel to said intermediate panel means to provide an air volume which is responsive to the vibrations imparted thereto,

(h) bridging post means securing said rear panel and intermediate panel together to impart to the rear panel the vibrations from said intermediate panel,

(i) there being opening means in said intermediate panel to communicate said air volumes,

(j) a bridging post connected from said larger area panel portion through said opening means and to said rear panel to conduct thereto vibrations from said larger area panel portion,

(k) said converting means, panel portions of said front panel, intermediate panel, rear panel, and air volumes cooperating to stereophonically reproduce the total sound represented by the signal voltage.

5. The invention of claim 4 wherein said panel portion which is 60% to 75 of the total area of said front panel means also being approximately greater in thickness.

6. The invention of claim 4 wherein said panel portion which is to of the total area of said front panel means also being approximately 50% greater in thickness and wherein said intermediate panel is in the range from approximately /2 inch to 1 inch in thickness.

7. A sound reproducing instrument for stereophonically reproducing audio frequencies from a signal voltage the frequency and amplitude of which represent the total sound to be reproduced comprising,

(a) means for receiving a signal voltage the frequency and amplitude of which represent the total sound to be reproduced,

(b) means for converting the received signal voltage into vibrations the frequency and amplitude of which represent the total sound to be reproduced,

(c) a plurality of spaced parallel panel means, one of which is connected to said converting means whereby the vibrations from said converting means are imparted to said panel connected therewith,

(d) said panel means that is connected to said converting means having predetermined portions which predominate in portions thereof a selected frequency and amplitude of vibrations,

(e) means interconnecting said spaced panels to transmit the vibrations from said one panel to the other panels, and

(f) said spaced panels defining an air volume responsive to said panel vibrations to stereophonically reproduce the tot-al sound represented by the signal voltage.

References Cited in the file of this patent UNITED STATES PATENTS 

1. A SOUND REPRODUCING INSTRUMENT FOR STEREOPHONICALLY REPRODUCING AUDIO FREQUENCIES FROM A SIGNAL VOLTAGE THE FREQUENCY AND AMPLITUDE OF WHICH REPRESENT THE TOTAL SOUND TO BE REPRODUCED COMPRISING, (A) MEANS FOR RECEIVING A SIGNAL VOLTAGE THE FREQUENCY AND AMPLITUDE OF WHICH REPRESENT THE TOTAL SOUND TO BE REPRODUCED, (B) MEANS FOR CONVERTING THE RECEIVED SIGNAL VOLTAGE INTO VIBRATIONS THE FREQUENCY AND AMPLITUDE OF WHICH REPRESENT THE TOTAL SOUND TO BE REPRODUCED, (C) PANEL MEANS SECURED TO SAID CONVERTING MEANS WHEREBY THE VIBRATIONS ARE IMPARTED TO SAID PANEL MEANS, (D) ADDITIONAL PANEL MEANS SECURED TO BUT SPACED FROM SAID FIRST NAMED MEANS WHEREBY THE VIBRATIONS FROM SAID FIRST NAMED PANEL MEANS ARE ALSO IMPARTED TO SAID ADDITIONAL PANEL MEANS AND THE SPACE BETWEEN SAID PANEL MEANS AND ADDITIONAL PANEL MEANS PROVIDING AN AIR VOLUME IN WHICH THE VIBRATIONS MAY BE INDUCED, AND (E) SAID PANEL MEANS AND SAID ADDITIONAL PANLE MEANS HAVING PREDETERMINED AREAS WHICH SELECTIVELY CONCENTRATE FREQUENCY RANGE OF VIBRATIONS IN SAID PREDETERMINED AREAS OF SAID PANEL MEANS AND ADDITIONAL PANEL MEANS TO THEREBY STEREOPHONICALLY REPRODUCE THE TOTAL SOUND REPRESENTED BY THE SIGNAL VOLTAGE. 